Outboard motors which are used to propel watercraft are often powered by internal combustion engines. These engines do not run efficiently when they are too hot or too cold. For example, when the engine is hot, the combustion efficiency is greatly lowered. On the other hand, if the engine is cold, the lubricating system may not function properly.
Typically, these engines are cooled with a liquid cooling system. In this system, water is drawn from the body of water in which the motor is operating by a pump. The pump delivers the water directly from the body of water to the water passages or jackets within the engine for cooling its various parts.
A problem is encountered with this type of cooling system when the motor is operated in cold water, such as in the winter. In this event, very cold water is continuously drawn into the cooling system. This cold water prevents the engine from warming up. Further, if a thermostat is used to prevent the passage of water through the engine for some time while it warms up, the cold water must eventually flow through the engine to cool it. The temperature gradient at the interface between the hot engine and cold water can be damaging to various of the engine parts.
At the same time, any cooling system which is utilized must be simple, and should allow the lubricant in the lubricating system to both achieve a proper operating temperature but prevent it from overheating.
A cooling system for an engine of an outboard motor which achieves the above-stated goals is desired.